Low serum brain derived neurotrophic factor in non-suicidal out-patients with depression: Relation to depression scores

Context: Low brain-derived neurotrophic factor (BDNF) has been implicated in the pathophysiology of depression. The relation between BDNF and severity of depression has been investigated. Aims: In this study, we aimed to measured serum BDNF levels in never-treated non-suicidal out-patients with depression and relate this to the severity of depression. Settings and Design: This study was conducted in an out-patient setting in a tertiary care psychiatric hospital on consenting depressed patients. Materials and Methods: Forty three (19 females) antidepressant-naive out-patients with depression, aged between 18 and 55 years and 24 (13 females) age-matched healthy volunteers gave consent for the study. Serum BDNF levels were assayed by using the sandwich enzyme-linked immunosorbent assay method on morning serum samples before starting treatment. These were compared between patients and controls using independent sample t-test. Pearson's correlation coefficient was used to assess the association between baseline BDNF and Hamilton depression rating scale (HDRS). Results: Serum BDNF was significantly lower in patients with depression (mean +/- standard deviation (SD)=18.59 +/- 4.9 ng/ml) than in healthy volunteers (mean +/- SD=23.6 +/- 5.6 ng/ml; P=0.001). There was a significant negative correlation between the HDRS total scores and BDNF levels (P=0.04), indicating that more severely depressed patients had lower BDNF scores. Conclusions: Serum BDNF level is lower in non-suicidal out-patients with depression. The inverse correlation between ratings of depression and BDNF levels suggests possible relationship between depression, (role of illness on) BDNF levels and neuroplasticity thereof.